OK... final grasp at a straw - your set of chairs for when they are not visiting, and when extended family come over, bring out fold out chairs with washable slipcovers? I know how difficult it is when you want to have a room that you like but you are having to adapt it for just for the one-off occasions and not as you would like it ideally. Perhaps that might work so you get what you want (most of the time!)

You could go wider but it depends on what type of dining furniture would want to use and how many you will be catering for. Bench seating tucks underneath and when it is being used you aren't so worried about the other space. You could always turn it around the other way [ perpendicular to the house] so the width is less of an issue as 10 metres is a decent length deck. I think even an extra 30cm would make a difference and not doing it may cost more in regret than the materials. You could go wider in the dining area only but it is a bit hard to judge without seeing the space. Find some furniture you like online and map out a plan for yourself - use newspaper for life size modelling. Good luck

Maybe try Asian/Balinese style business or look at pinterest: that will give you idea that you could take to a tradesman and get a quote on bespoke or if you have a male that is very handy some great ideas on that link. https://www.pinterest.com.au/pin/419679259009258301/

Mimosa has a similar product. Without knowing the actual furniture manufacturer, mimosa may be a good alternative.